Imaging device

Abstract

An imaging device is provided with: a plurality of pixels, each pixel including a photoelectric converter that converts light into a signal charge and a charge accumulator that accumulates the signal charge, and each pixel outputting a pixel signal VSIG corresponding to an amount of the signal charge accumulated in the charge accumulator; a first conversion circuit that converts the pixel signal VSIG into a first digital signal; and a second conversion circuit that converts the pixel signal VSIG into a second digital signal with a lower resolution than the first digital signal. The imaging device generates first image data containing the first digital signal and second image data containing the second digital signal.

What is claimed is: 
     
         1 . An imaging device comprising:
 a plurality of pixels, each pixel including a photoelectric converter that converts light into a signal charge and a charge accumulator that accumulates the signal charge, and each pixel outputting a signal corresponding to an amount of the signal charge accumulated in the charge accumulator;   a first conversion circuit configured to convert the signal into a first digital signal; and   a second conversion circuit configured to convert the signal into a second digital signal, a resolution of the second digital signal being less than a resolution of the first digital signal, wherein   the imaging device generates first image data containing the first digital signal and second image data containing the second digital signal.   
     
     
         2 . The imaging device according to  claim 1 , wherein the first conversion circuit converts the signal read out non-destructively into the second digital signal. 
     
     
         3 . The imaging device according to  claim 1 , wherein the second conversion circuit includes an inverter circuit. 
     
     
         4 . The imaging device according to  claim 3 , wherein the inverter circuit includes an inverter with a variable threshold voltage. 
     
     
         5 . The imaging device according to  claim 1 , wherein the second conversion circuit includes a differential amplifier. 
     
     
         6 . The imaging device according to  claim 1 , wherein the first conversion circuit and the second conversion circuit include a shared counter. 
     
     
         7 . The imaging device according to  claim 1 , wherein the first conversion circuit and the second conversion circuit include a shared latch. 
     
     
         8 . The imaging device according to  claim 1 , wherein
 the first conversion circuit includes a comparator that compares the signal with a reference signal, and   the second conversion circuit does not include a comparator that uses the reference signal.   
     
     
         9 . The imaging device according to  claim 1 , further comprising:
 a signal processing circuit to which the first image data and the second image data are input.   
     
     
         10 . The imaging device according to  claim 9 , wherein the signal processing circuit includes a frame memory that holds the second image data. 
     
     
         11 . The imaging device according to  claim 9 , wherein
 the imaging device generates a plurality of the second image data under mutually different imaging conditions, and   the signal processing circuit outputs a merged image obtained by integrating the plurality of second image data.   
     
     
         12 . The imaging device according to  claim 1 , wherein the second conversion circuit converts the signal into the second digital signal multiple times in a period, within one frame period, during which the signal is not destroyed. 
     
     
         13 . The imaging device according to  claim 1 , further comprising:
 a control circuit, wherein   the control circuit adjusts imaging conditions based on the second image data.   
     
     
         14 . The imaging device according to  claim 13 , wherein the control circuit determines imaging conditions for generating the first image data in a second period after a first period, based on the second image data containing the second digital signal converted by the second conversion circuit from the signal corresponding to the amount of the signal charge converted by the photoelectric converter in the first period. 
     
     
         15 . The imaging device according to  claim 1 , further comprising:
 a control circuit, wherein   the control circuit performs the following in a period, within one frame period, during which the signal is not destroyed:
 the control circuit repeatedly causes the second conversion circuit to convert the signal into the second digital signal until the second image data meets a prescribed condition; and 
 once the second image data meets the prescribed condition, the control circuit causes the first conversion circuit to convert the signal into the first digital signal. 
   
     
     
         16 . The imaging device according to  claim 1 , further comprising:
 a control circuit, wherein   the control circuit performs the following in a period, within one frame period, during which the signal is not destroyed:
 the control circuit repeatedly causes the second conversion circuit to convert the signal into the second digital signal until the second image data meets a prescribed condition; and 
 the control circuit outputs the second image data that meets the prescribed condition. 
   
     
     
         17 . The imaging device according to  claim 1 , wherein the resolution of the second digital signal is 4 or less. 
     
     
         18 . The imaging device according to  claim 17 , wherein the resolution of the second digital signal is 2. 
     
     
         19 . The imaging device according to  claim 1 , further comprising:
 a signal line to which the signal is input, wherein   the first conversion circuit and the second conversion circuit are connected to the signal line in parallel.   
     
     
         20 . An imaging device comprising:
 a plurality of pixels, each pixel including a photoelectric converter that converts light into a signal charge, and each pixel outputting a signal corresponding to an amount of the signal charge; and   a conversion circuit configured to convert the signal into a digital signal, a resolution of the digital signal being 2, wherein   the imaging device generates image data containing the digital signal.